Railway crossings, sometimes referred to as “railroad crossings,” “grade crossings,” or “level crossings,” are traffic intersections of railways and roadways (such as vehicular roads, paths, highways, or freeways) on the same plane. In typical configurations, railways and roadways are orthogonal, angled, or otherwise not parallel inside of the railway crossing. Trains and other rail vehicles are typically given the right of way inside of railway crossings because their significant mass and high speed makes it impossible or commercially impractical for them to stop at every railway crossing along a route.
The significant mass and speed of trains, and thus their kinetic energy, unfortunately also presents significant risk of fatal collisions with passenger and other road vehicles inside of railway crossings. It is estimated that over 300 people are killed each year in the U.S. alone in railway crossing collisions. In one example, a freight train collided with a municipal bus carrying impaired seniors and young adults in a Pennsylvania intersection in April 2013 resulting in the death of one passenger and the hospitalization of nearly a dozen others.
In an effort to prevent collisions between trains and vehicles in railway crossings, various safety systems have been used. The safety systems can be classified as passive or active. Passive safety systems may include safety devices such as warning signs, lights, and/or other devices which are placed and designed to notify or warn drivers of vehicles that the intersection contains a railway that might have an approaching train and that they should proceed with caution. Active safety systems may contain safety devices such as audible notification devices (such as bells or horns), visual notification devices (such as lights), barriers (also known as “preclusion devices”, such as mechanical crossing gates, sometimes referred to as “boom gates”), and/or other devices which are placed and designed to notify drivers of vehicles that a train is approaching, has entered, or is within the intersection. In a typical configuration, an active safety system may include mechanical crossing gates on both sides of the roadway. When a train is approaching or within the intersection, the mechanical crossing gates descend above the roadway preventing vehicles from entering the intersection. The active safety systems can further include visual notification to drivers of vehicles, such as lights, which may be placed on the gates, or audible notification, such as bells.
Active railway safety system designs are varied, though most contain some form of electronic circuitry to identify an approaching train, and activate the notification devices and/or barriers. The circuitry is contained in a “signal house” (or “signal case”) and is maintained by a qualified railway person known as a signalman. In the simplest form, the safety system may electronically sense when an approaching train is within a certain distance from the intersection, and then activate the notification devices and barriers may be activated. In more complex safety systems, the safety system may be interconnected to other crossings or system controllers, and may be configured to coordinate with nearby roadway traffic control signals. The railway safety system may include relays, solid state or digital circuitry, computers, or programmable logic controllers for selectively activating and deactivating the safety devices. For example, relays may be associated with a safety device, such as a motor lowering and raising a gate, or a circuit activating light or a bell. In some systems, when the safety system detects an approaching train, a signal will be provided to the primary (or coil) of the relay to activate the safety device. Some conventional systems detect approaching trains by energizing the rails of a portion of the rail track, and detecting when the rails are shunted within the portion of the track by the train wheels and axles. Other conventional systems detect approaching trains by one or more tuned audio frequency detectors placed along the rail track to detect the proximity of a train near the audio frequency detectors. The railway safety systems typically have circuitry receiving the output of the detector and activating or deactivating the safety devices in response thereto, for example, by opening or closing a relay associated with the safety device. Some modern railway safety systems may also be configured to receive additional signals and activating or deactivating the safety devices in response thereto.
Unfortunately safety systems are prone to the occasional malfunction, which can result in dangerous collisions. In July 1967, a crossing gate got snagged with an overhead telegraph wire in a German railway crossing, which prevented the closure of the crossing gate. A railway worker manually opened the gate before the arrival of a train in order to free the snagged gate, however, he neglected to signal the train to stop before the intersection. A fuel tanker mistook the open crossing gate as an indication that it was free to pass, at which time it was struck by the train and exploded, causing the death of nearly 100 individuals.
When safety system malfunctions occur, or the safety system is otherwise needed to be maintained, railway personnel are called to fix the problem. Depending on the severity of the problem it may take hours or days to fix or maintain the safety system. In the interim, trains and vehicles still need to continue to use the intersection. The variability of railway intersections (i.e., some intersections may have only passive warning lights, while others may include one or more gates, while others may coordinate with roadway traffic control signals) and the variability of the electronic circuitry within the signal house or signal case makes it difficult for general railway personnel to manually control the intersection or fix the problem.
Some conventional approaches to overriding the railway safety system include jumping the contacts of the relay associated with the safety device so as to open or close the relay to manually activate or deactivate the safety device. In some instances, during a malfunction or maintenance, the signalman temporarily rewires the electronic circuitry (for example, by using jumper or patch cables) to cause a desired outcome at the railway intersection. For example, when a malfunction causes a gate to remain closed when there is no approaching train, a signalman may jumper portions of the electronic circuitry (such as jumping relay control terminals) to temporarily raise the crossing gates to permit vehicles to pass through the intersection. The signalman may also notify nearby train crews that there is a malfunction in, or maintenance of, the safety system such that they will approach with caution or notify the signalman of their impending approach so that the signalman can temporarily lower the gates by jumping portions of the electronic circuitry. Once the signalman has completed the repairs, he or she may remove all jumper or patchwork to return the electronic circuitry to its automated state.
It is to be appreciated that the circuitry within the signal house of one intersection may be different than the circuitry within the signal house of another intersection, thus access to the circuitry of the safety system is limited to select railway personnel that are qualified to maintain and knowledgeable with the signal house or signal case circuitry at a specific crossing. Non-qualified railway personnel are unable to override the railway safety system, and in most situations, only qualified signalmen may be capable of acting when a safety system malfunction occurs.
What is needed, therefore, is an apparatus which permits general railway personal without an understanding of the safety system circuitry, and without access to the circuitry within the signal house, to temporarily override portions of a railway safety system.